Principal photography had to be restarted three times from scratch. Once because the actor who was originally casted to play the Man quit after a couple days of shooting, and the crew had to find a replacement. Next time because of the conflict between the initial DP and the main actress (the DP left, and again the crew had to find a replacement). But on the third attempt everything went as great as it was planned.
Composer Kim Astakhov recorded accordion for the waltz using his digital synthesizer. On the first take he recorded the accordion sounds, and on the second take he recorded the clicks of the keys to achieve a live instrument effect.
100% of the dialogue was automatically replaced to achieve specific nuances in actors' performance.